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MXS-3892: Delay routing instead of canceling it

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Putting the sessions that aren't doing the update on hold makes the new
mechanism work the same way the old one did with the exception that it
won't put any extra work on the database itself.
This commit is contained in:
Markus Mäkelä 2021-12-24 07:13:08 +02:00
parent 41c2a6ee8e
commit 56ea0db3e6
No known key found for this signature in database
GPG Key ID: 5CE746D557ACC499
2 changed files with 50 additions and 4 deletions
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52
server/modules/routing/schemarouter/schemaroutersession.cc
View File

@ -101,6 +101,11 @@ void SchemaRouterSession::close()
{
m_closed = true;
if (m_dcid)
{
mxb::Worker::get_current()->cancel_delayed_call(m_dcid);
}
for (SSRBackendList::iterator it = m_backends.begin(); it != m_backends.end(); it++)
{
SSRBackend& bref = *it;
@ -287,7 +292,7 @@ int32_t SchemaRouterSession::routeQuery(GWBUF* pPacket)
return 0;
}
if (m_shard.empty())
if (m_shard.empty() && (m_state & INIT_MAPPING) == 0)
{
// Check if another session has managed to update the shard cache
m_shard = m_router->m_shard_manager.get_shard(m_key, m_config->refresh_min_interval);
@ -303,10 +308,17 @@ int32_t SchemaRouterSession::routeQuery(GWBUF* pPacket)
else
{
// Too many concurrent updates
m_queue.push_back(pPacket);
// TODO: Queue this session instead of killing it
m_pSession->kill(modutil_create_mysql_err_msg(1, 0, 1096, "HY000", "Too many updates"));
return 0;
if (m_dcid == 0)
{
// Wait for the other session to finish its update
auto worker = mxs::RoutingWorker::get_current();
m_dcid = worker->delayed_call(1000, &SchemaRouterSession::delay_routing, this);
MXS_INFO("Waiting for the database mapping to be completed by another session");
}
return 1;
}
}
}
@ -1105,6 +1117,37 @@ void SchemaRouterSession::route_queued_query()
session_delay_routing(m_pSession, router_as_downstream(m_pSession), tmp, 0);
}
bool SchemaRouterSession::delay_routing(mxb::Worker::Call::action_t action)
{
bool rv = false;
if (action == mxb::Worker::Call::EXECUTE)
{
mxb_assert(m_shard.empty());
m_shard = m_router->m_shard_manager.get_shard(m_key, m_config->refresh_min_interval);
if (!m_shard.empty())
{
MXS_INFO("Another session updated the shard information, reusing the result");
route_queued_query();
m_dcid = 0;
}
else if (m_router->m_shard_manager.start_update(m_key))
{
// No other sessions are doing an update, start our own update
query_databases();
m_dcid = 0;
}
else
{
// We're still waiting for an update from another session
rv = true;
}
}
return rv;
}
/**
*
* @param router_cli_ses Router client session
@ -1477,6 +1520,7 @@ enum showdb_response SchemaRouterSession::parse_mapping_response(SSRBackend& bre
*/
void SchemaRouterSession::query_databases()
{
MXS_INFO("Mapping databases");
for (SSRBackendList::iterator it = m_backends.begin(); it != m_backends.end(); it++)
{

2
server/modules/routing/schemarouter/schemaroutersession.hh
View File

@ -148,6 +148,7 @@ private:
int inspect_mapping_states(SSRBackend& bref, GWBUF** wbuf);
enum showdb_response parse_mapping_response(SSRBackend& bref, GWBUF** buffer);
void route_queued_query();
bool delay_routing(mxb::Worker::Call::action_t action);
void synchronize_shards();
void handle_mapping_reply(SSRBackend& bref, GWBUF** pPacket);
bool handle_statement(GWBUF* querybuf, SSRBackend& bref, uint8_t command, uint32_t type);
@ -170,5 +171,6 @@ private:
uint64_t m_sent_sescmd; /**< The latest session command being executed */
uint64_t m_replied_sescmd;/**< The last session command reply that was sent to the client */
SERVER* m_load_target; /**< Target for LOAD DATA LOCAL INFILE */
uint32_t m_dcid {0};
};
}